1. Field of the Invention
This invention relates to a disk drive suspension comprising a microactuator element of, for example, lead zirconate titanate (PZT).
2. Description of the Related Art
A hard disk drive (HDD) is used in an information processing apparatus, such as a personal computer. The HDD comprises a magnetic disk rotatable about a spindle, a carriage turnable about a pivot, etc. The carriage, which comprises an actuator arm, is configured to be turned transversely relative to tracks of the disk about the pivot by a positioning motor, such as a voice coil motor.
A suspension is mounted on the actuator arm. The suspension comprises a load beam and flexure superposed thereon. A slider, which constitutes a magnetic head, is mounted on a gimbal portion formed near the distal end of the flexure. The slider is provided with elements (transducers) for accessing data, that is, for reading or writing data. The load beam, flexure, slider, etc., constitute a head gimbal assembly.
In order to overcome the increase in the recording density of disks, the magnetic head should be more precisely positioned relative to the recording surface of each disk. To attain this, dual-stage-actuator (DSA) suspensions have been developed that combine a positioning motor (voice coil motor) and microactuator element made of a piezoelectric material, such as lead zirconate titanate (PZT).
The distal end of the suspension can be quickly moved by an infinitesimal distance in a sway direction (or transversely relative to tracks) by applying a voltage to and thereby deforming the actuator element. As disclosed in Jpn. Pat. Appln. KOKAI Publications Nos. 2010-146631 (Patent Document 1) and 2010-218626 (Patent Document 2), moreover, there are known DSA suspensions in which a microactuator element is disposed on a gimbal portion of a flexure.
In a head gimbal assembly in which a slider and microactuator element are mounted on a gimbal portion, the microactuator element is secured to the gimbal portion by an adhesive. For electrical conduction between a conductive circuit portion and an electrode of the microactuator element, moreover, an electrically conductive paste, such as a silver paste, is applied to a conductor of the conductive circuit portion. An electrode part of the microactuator element is superposed on the paste.
In the case of such a conventional joint structure, an adhesive surface between the electrode part of the microactuator element and the electrically conductive paste is parallel to the direction of extension and contraction (stroke direction) of the microactuator element. Thus, an in-plane shearing force is applied to the adhesive surface as the microactuator element extends and contracts. The electrically conductive paste on the adhesive surface is more fragile and less adhesive than an adhesive, such as an epoxy resin. If the in-plane shearing force is repeatedly applied to the adhesive surface, slippage may occur on the adhesive surface, resulting in separation of the adhesive surface. The separation of the adhesive surface causes defective continuity. In the case where a slit for electrical insulation is formed in a part of the peripheral surface of the microactuator element, the electrically conductive paste is located near the slit. Accordingly, the paste may get into the slit, thereby causing an inter-electrode short circuit.
According to another conventional example, a conducting member, such as a lead wire or bonding wire, may be connected to the electrode of the microactuator element so that they electrically conduct to each other. In this case, the conducting member is disposed near the surface of the microactuator element. Possibly, therefore, the element may be damaged by contact with the conducting member if subjected to external mechanical shock.